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Help needed desperately with PIC LCF meter

Discussion in 'General Electronics Chat' started by bigal_scorpio, May 2, 2008.

  1. kasamiko

    kasamiko Member

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    Nothing i can say....Me too just planning to build this stuff...:(
     
  2. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi lynx,
    I am not ignoring you, its just I cannot think of a quick fix.
    A number of members have built this project and it runs OK, also you said that your build was working OK until you modified it.

    I would suggest that you restore the project back to its original design, [ the one that works], this may highlight what has caused the problem..
    It sounds as though you have a floating input on the IC.???
     
  3. lynx

    lynx Member

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    hi ericgibbs and sorry that i complained :)
    i really need to fix this instrument because it's useful to me...

    concerning the floating input you said... i guess such thing can happen
    in case i forgot rewire any of the cables that used to go to the rottery swich
    right?
     
  4. dave

    Dave New Member

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  5. bigal_scorpio

    bigal_scorpio Active Member

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    Hi Lynx,

    Like Eric I am struggling to imagine whats going wrong.

    I have looked over my original schematic and circuit drawing and can't see anything that would give the false readings WITHOUT giving other symptoms.

    I am posting the original PDF so you can examine and fault find from it in case you don't still have it but without actually seeing your mods I don't think anyone will be able to help much. What about some really clear pics of the board and wiring?

    Al
     

    Attached Files:

    • 02.pdf
      File size:
      462.8 KB
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  6. kasamiko

    kasamiko Member

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    style struggling for 3.xxx mhz xtal..:(
     
  7. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi Al,
    I still have all our notes/drawings on my hard drive, under 'Al's Stuff'...:)

    I feel sure that the latest OP has a wiring error in his converted version, most likely an open CMOS input or missing ground link.
     
  8. bigal_scorpio

    bigal_scorpio Active Member

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    Hi Eric,

    Hope you're keeping well mate, like you I seem to think that the changes made may have caused something to go awry.

    Apart from the problem I had building this, which was the missing R/W ground that you pointed out I have not heard anyone say theirs was faulty.

    Your advice stands - put it back to original. I don't understand why he modified it unless it was size considerations as the 3 pole switches are a bit space hungry!

    Al
     
  9. bigal_scorpio

    bigal_scorpio Active Member

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    Hi mate,

    Do you still need the 3.2768mHz crystal?

    If you do then PM me your address and I will send you one.

    Al
     
  10. kasamiko

    kasamiko Member

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    Thanks for the offer mate..But I'm from the Philippines...:( The cost of shipping I think is enough to buy a dozen of xtals..:D
     
    Last edited: Mar 15, 2011
  11. lynx

    lynx Member

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    Hi

    sorry for my delay to reply to this topic
    here's a photo of my wiring...

    if we can make it work right.. it would be great!! :)
     

    Attached Files:

    • LCF.jpg
      LCF.jpg
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  12. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi lynx,
    Post a picture of both sides of the PCB, showing the whole board surfaces.
    It may be possible to trace the problem from the pics.
     
  13. lynx

    lynx Member

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    ok thanks for your support! :)
    here's more photos..
     

    Attached Files:

  14. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi,
    Got your pics, I will look them over...
    EDIT:

    Check this track for a break at this point... I will keep looking.

    EDIT2:
    It appears C7 is also missing.... 1nF see 3rd image
     

    Attached Files:

    Last edited: Mar 21, 2011
  15. lynx

    lynx Member

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    Hi

    unfortunately that's not a track break..it's just a scratch and the copper
    is visible, but it's great that you noticed such a little detail in a photo :)

    C7 is not missing it's the capacitor between the two resistors.

    can the problem be the crystal? but the PIC starts...
     
  16. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi.
    I understand you just want to use the Inductor section of the LCF.??

    If so, this image shows all you need for the oscillator section.
     

    Attached Files:

  17. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi,
    As you dont want the CAP function, you can modify the pcb as shown in this image.
     

    Attached Files:

    • back.jpg
      back.jpg
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  18. lynx

    lynx Member

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    ok i'll try your mod later...
    and i'll let you know :)
     
  19. paul_costin

    paul_costin New Member

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    Hello everyone, I would like to build the LCF meter, but first I would to simulate it in Proteus Isis 7. It doesn`t display only 0Hz or Inductor Timing , using the code uploaded by bigal_scorpio for PIC16F628A . Could anyone help me please? I could try to send the project and lake a look at it . I`m an amateur and trying to learn electronics. Thank you
     
  20. lynx

    lynx Member

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    Hi..

    still frequency and inductor values go up and down

    with a 3.3uH inductor it says:

    18027Hz
    15.802uH

    18039Hz
    9.024uH

    18002Hz
    29.364uH

    etc......
     
    Last edited: Mar 25, 2011
  21. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi lynx,
    If you are in the UK, you could post your project to me and I will fix and return.
     

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